With the rapid advances in the integrated circuit (IC) packaging technology and the great promotion of operation performance, not only multi-media computers are widely favored by consumers, but also popularization of computers and the related peripheral products are accelerated. However, because of improvements in IC's operation performance, the number of the packaging contact pins of various components is also greatly increased. This leads that the related circuit board layout design becomes more sophisticated and complicated and that the manufacturing processes for plugging and tin soldering of circuit boards meet with considerable difficulties. In current production procedures in assembly of circuit boards, the manufacturing process for tin soldering the contact pins of the chips is mainly by means of wave soldering, wherein the molten liquid tin inside the stannic furnace is gushed up by a pump as a long tin wave and when the circuit board is obliquely transported upwardly through the stannic furnace and makes contact with the tin wave, the liquid tin will enter into the holes where the contact pins of the chip are plugged in the circuit board, fill the tin therein, and form weld spots thereon.
Please refer to FIG. 1, which is a schematic diagram of a bottom view of a conventional tooling frame, including a main frame 10 which is a frame structure designed in accordance with the shape and dimension of a circuit board 12. The surface 14 of the circuit board 12 to be soldered faces downward to a stannic furnace (not shown) and the rims of the circuit board 12 are held on the main frame 10 to expose the soldering region of the circuit board 12 from the hollow portion in the middle of the main frame 10. Hence, the conventional tooling frame has merely one major function that is to support the circuit board 12 so as to prevent the circuit board 12 from bending or deforming when transferred through the stannic furnace for wave soldering. However, it is found that in the process of wave soldering, the output yield of the circuit board 12 through the stannic furnace is much concerned with contact pins 18 of a chip 16. Especially, when the number of contact pins 18 of the chip 16 become more and the arrangement thereof grow denser, the weld spot formed at the rear area of the contact pin 18 of the chip 16, as shown by the arrow in FIG. 2 which is a side view of part of the conventional tooling frame, is more liable to has the defects such as tin bridge or poor tin filling etc.
Although the above-mentioned problems may be later remedied by operators to remove the tin bridge and poor filling tin in order to maintain the soldering quality of the circuit board, such an action not only increases labor costs, but also the quality of circuit boards becomes uncontrollable due to the human factor. Therefore, the manufacturers of circuit boards are devoted to development and improvement in the producing and manufacturing processes in order to greatly decrease the probability of tin bridge and poor tin filling defects occurred at the weld spots of the contact pins of the circuit board during the wave soldering, and to enhance the soldering quality of circuit boards as well as to reduce labor costs.